Method and apparatus for providing voice signals to and from a telecommunications switch

ABSTRACT

A voice gateway ( 64 ) includes an input port ( 70 ) that receives a voice signal from an unbundled analog line ( 62 ) coupled to a Class  5  switch ( 52 ). The voice signal is converted to a digital format by an analog-to-digital and digital-to-analog converting unit ( 76 ). The voice signal is placed into a compressed format by a compressing/decompressing unit ( 80 ) using a selected one of a plurality of compression ratios. The voice signal is placed into a transport frame by a packetizing/depacketizing unit ( 84 ) according to a selected packet format. The voice signal is multiplexed with other voice signals by an output port ( 88 ). The output port ( 88 ) places the voice signal onto a selected one of a plurality of output lines in order to transport the voice signal in its transport frame to one of an office customer premises ( 12 ) and a residence customer premises ( 14 ).

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.09/356,250, filed Jul. 16, 1999 now U.S. Pat. No. 6,512,764, by A. J.Paul Carew, Ronald D. Lutz, Jr., and Brendon W. Mills and entitled“Method and Apparatus for Providing Voice Signals to and from aTelecommunications Switch,”

TECHNICAL FIELD OF THE INVENTION

The present invention relates in general to telecommunications signalprocessing and more particularly to a method and apparatus for providingvoice signals to and from a telecommunications switch.

BACKGROUND OF THE INVENTION

The traditional circuit switched telecommunications network has beenimplemented to dedicate one voice line to one loop or copper pair. Thishas worked well for over a hundred years but does not efficientlyutilize the bandwidth of the copper pair. In addition, there has been asurge in demand for second, and even third, residential phone lines.This demand is exhausting the supply of available copper circuits.Business customers also have a high demand for phone lines. To meet thisdemand, Regional Bell Operating Companies, Independent Local ExchangeCarriers, and Competitive Local Exchange Carriers would have to buildadditional copper or fiber infrastructure.

New technology, such as Digital Subscriber Line, voice-over-IP, andasynchronous transfer mode techniques have created an environment wherethe copper pair's available bandwidth can be more fully utilized tocarry voice and data. However, traditional voice traffic is timedivision multiplexed, a transport architecture that segments the networkbandwidth into fixed time sequenced channels. The smallest channel isequivalent to a voice line. Time division multiplexed networks work wellfor uncompressed analog voice but not for bursty data. If a data networkneeds more than 64 kilobits per second of bandwidth, the amount of onechannel, two channels would be needed to carry 65 kilobits per second,resulting in bandwidth inefficiencies.

With the explosion of the Internet, worldwide deployment of DigitalSubscriber Lines will rapidly accelerate over the next few years. Today,however, the penetration rate for voice over DSL is at zero percent.With the increase in their deployment, DSL is a prime candidate forimplementing a multiple voice line capability for telecommunicationscustomers. There have been recent efforts to provide voice over DSL.However, these efforts have required a GR-303 connection with a Class 5switch for the gateway device. This GR-303 connection is available atthe regional bell operating company or independent local exchangecarrier level but competitive local exchange carriers would need toprovide there own Class 5 switch or digital loop carrier functionalityto interface with the GR-303 connection. In order to implement thisfunctionality, competitive local exchange carriers would have to incurcostly expense in providing this infrastructure. Therefore, it isdesirable to migrate voice services into the data transport network inorder to efficiently use the bandwidth of the copper pair and avoidexpensive infrastructure changes in allowing a competitive localexchange carrier to implement an increased and efficient voice transportcapability.

SUMMARY OF THE INVENTION

From the foregoing, it may be appreciated that a need has arisen toefficiently provide voice signal transport without bandwidthinefficiency. In accordance with the present invention, a method andapparatus for providing voice signals to and from a telecommunicationsswitch are provided which substantially eliminate or reducedisadvantages and problems associated with conventional voice transporttechniques.

According to an embodiment of the present invention, there is providedan apparatus for providing voice signals from a telecommunicationsswitch that includes an input port operable to receive an unbundledanalog line from the telecommunications switch, wherein a voice signalis carried over the analog line. An analog-to-digital converter unitconverts the voice signal carried on the analog line into a digitalformat. A compressing unit places the voice signal into a compressedformat. A packetizing unit places the voice signal into a packet formatfor transport over a data network.

The present invention provides various technical advantages overconventional voice transport techniques. For example, one technicaladvantage is to provide unbundled analog line ports to a competitivelocal exchange carrier without the need for an overlay Class 5 switch ordigital loop carrier architecture. Another technical advantage is tomimic the dynamic allocation of timeslots of a standard GR-303 interfacewithout utilizing that interface in order to provide an oversubscriptioncapability. Yet another technical advantage is the ability to support amultitude of voice transport framing philosophies. Still anothertechnical advantage is to provide selective compression and packetizingcapabilities for versatile voice transport operation. Other technicaladvantages may be readily apparent to those skilled in the art from thefollowing figures, description, and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention and theadvantages thereof, reference is now made to the following descriptiontaken in conjunction with the accompanying drawings, wherein likereference numerals represent like parts, in which:

FIG. 1 illustrates a block diagram of a telecommunications network;

FIG. 2 illustrates a block diagram of a voice gateway within thetelecommunications network.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a block diagram of a portion of a telecommunications network10. Telecommunications network 10 includes one or more office customerpremises 12, one or more residence customer premises 14, one or moreinformation service providers 16, one or more independent local exchangecarrier central offices 18, and one or more competitive local exchangecarriers 20.

Office customer premises 12 may receive data and voice at an IntegratedAccess Device (IAD) 22. IAD 22 may provide data and voice to a privatebranch exchange 24 in order to support telephony operations at telephonydevices 25 within office customer premises 12. IAD 22 may also providedata and voice to a local area network 26 through a router 27. Localarea network 26 may have computers or other devices 28 connected theretofor processing the data and voice received from IAD 22 in order tosupport computer processing and telephony capability over local areanetwork 26. Data and voice generated by devices 25 and 28 connected tolocal area network and private branch exchange 24 may also betransferred out of office customer premises 12 by IAD 22.

Residence customer premises 14 may receive data and voice at an IAD 30.IAD 30 may provide data and voice to telephony devices 32 and also tocomputing devices 34 connected thereto. Data and voice generated byeither telephony devices 32 or computing devices 34 or both may betransferred out of residence customer premises 14 through IAD 30.

Information service provider 16 may receive data at an Internet gateway40 from competitive local exchange carrier 20. Internet gateway 40provides the interface to Internet 42. Information service provider 16supports connections to Internet 42 for the passage of data thereto andtherefrom through Internet gateway 40 as received from or provided tocompetitive local exchange carrier 20.

Independent local exchange carrier central office 18 may receive dataand voice carried by a public switched telephone network 50. A Class 5switch 52 is the interface to and from public switched telephone network50. Class 5 switch 52 passes voice and data received from publicswitched telephone network 50 to competitive local exchange carrier 20.Competitive local exchange carrier 20 provides voice and data to officecustomer premises 12 and residence customer premises 14 from Class 5switch 52. Voice and data may be received from office customer premises12 and residence customer premises 14 by competitive local exchangecarrier 20 for transfer to Class 5 switch 52.

Competitive local exchange carrier 20 includes a voice gateway 64receives voice and data from and provides voice and data Class 5 switch52. Unbundled analog line connections 62 are provided from Class 5switch 52 to voice gateway 64. By providing a capability to interconnectto Class 5 switch 52 using standard unbundled analog lines 62,competitive local exchange carrier 20 is able to provide voicefunctionality over its broadband network without needing its own overlayClass 5 switch or digital loop carrier architecture. A DigitalSubscriber Line Access Multiplexer (DSLAM) device 66 provides aninterface for voice and data with office customer premises 12 andresidence customer premises 14. DSLAM device 66 and voice gateway 64pass voice and data to and from each other or to and from informationservice provider 16 through a packet switch 68. Packet switch 68 mayoperate using any of a variety of packet techniques to includeasynchronous transfer mode and frame relay. Voice and data may betransferred throughout telecommunications network 10 in any of a varietyof packet formats to include asynchronous transfer mode cells, framerelay packets, and Internet protocol. Competitive local exchange carrier20 may also implement multiple packet switches 68, each using adifferent packet technique. Though shown, competitive local exchangecarrier 20 need not be colocated with independent local exchange carriercentral office 18.

For voice operation from public switched telephone network 50, a voicesignal is transferred over public switched telephone network 50 to Class5 switch 52. Class 5 switch 52 routes the voice signal to voice gateway64 over an unbundled analog line 62. Voice gateway processes the voicesignal for transfer to DSLAM device 66 through packet switch 68. Theprocessing that may be performed by voice gateway 64 may includemultiplexing, analog-to-digital conversion, compression, andpacketizing. DSLAM device 66 provides the voice signal to its intendeddestination, such as office customer premises 12 or residence customerpremises 14.

For voice operation to public switched telephone network 50, a voicesignal is generated at, for example, office customer premises 12 andtransferred to DSLAM device 66. DSLAM device 66 receives the voicesignal from office customer premises 12 and prepares the voice signalfor transport over packet switch 68 to voice gateway 64. Upon receipt ofthe voice signal, voice gateway 64 converts the voice signal into itsappropriate analog format for transfer over an unbundled analog line 62.The unbundled analog line 62 carries the voice signal to Class 5 switch52. Class 5 switch 52 transfers the voice signal to its appropriatedestination on public switched telephone network 50.

Voice gateway 64 provides a capability to packetize and compress circuitswitched voice circuits from public switched telephone network 50 anddeliver them over broadband networks to business and residentialcustomers. With this capability, telecommunications service providersmay offer, according to the preferred embodiment, twenty-fourindependent voice lines over one Digital Subscriber Line circuit. Voicegateway 64 supports a variety of types of network framing, such as voiceover asynchronous transfer mode and voice over Internet protocol.Additionally, voice gateway 64 supports the latest in voice compressiontechnologies so that calls placed through voice gateway 64 sound similarto calls placed over public switched telephone network 50. Multiplephone lines can be imbedded into the broadband data stream andadditional lines can be added or subtracted on demand over a singlecopper circuit.

FIG. 2 is a block diagram of voice gateway 64. Voice gateway 64 includesan input port 70 to receive and provide voice signals from and tounbundled analog lines 62 of Class 5 switch 52. An analog-to-digital anddigital-to-analog converter unit 76 includes A/D and D/A converters 78that convert voice signals received from unbundled analog lines 62 intoa digital format and convert voice signals transferred to unbundledanalog lines 62 into an analog format. A compressing/decompressing unit80 includes compressors/decompressors 82 that compress voice signalsreceived from A/D and D/A converters 78 into a compressed format anddecompress voice signals prior to conversion into analog format. Apacketizing unit 84 includes packetizers/depacketizers 86 that packetizevoice signals into a packet format and depacket voice signals from thepacket format prior to decompression. An output port 88 provides voicesignals to and receives voice signals from DSLAM device 66 throughpacket switch 68. Output port 88 is capable of multiplexing multiplevoice signals together through interleaving of packets of differentvoice signals onto an output line to packet switch 68. Output port 88may also selectively place any voice signal onto any of its output linesaccording to the destination characteristics of each voice signal. Forexample, output port may multiplex five voice signals onto a firstoutput line and multiplex three other voice signals onto a second outputline.

Compressors/decompressors 82 may implement different compression ratios.For example, compressor/decompressor R1 may perform voice compressionusing the standard G.711 compression technique of 64 kilobits per secondpulse code modulation. Compressor/decompressor R2 may perform voicecompression using the standard G.722 compression technique of 32kilobits per second adaptive differential pulse code modulation.Compressor/decompressor R3 may perform voice compression using thestandard G.726 compression technique of 16 kilobits per secondcompression. Whichever compression technique is selected for a voicesignal, a customer experience of placing a call through voice gateway 64will be indistinguishable from a call placed only over public switchedtelephone network 50. Selection of which compression technique toperform on a particular voice signal is determined by the configurationof a first switching matrix 90. First switching matrix 90 is capable ofdynamically routing any voice signal received to any one ofcompressors/decompressors 82 in order to support selective compressionof voice signals. Appropriate decompression is also performed followedby selective routing through first switching matrix 90 to an appropriateA/D and D/A converter 78.

Packetizers/depacketizers 86 may implement different transport framingphilosophies. For example, packetizer/depacketizer P1 may packetize thevoice signal into asynchronous transfer mode cells.Packetizer/depacketizer P2 may packetize the voice signal into framerelay packets. Packetizer/depacketizer P3 may packetize the voice signalinto an Internet protocol format. The Internet protocol format may thenbe carried in the asynchronous transfer mode or frame relay format.Selection of which packetizing technique to perform on a particularvoice signal is determined by the configuration of a second switchingmatrix 92. Second switching matrix 92 is capable of dynamically routingany voice signal received to any one of packetizers/depacketizers 86 inorder to support selective packetizing of voice signals. Appropriatedepacketizing is also performed followed by selective routing throughsecond switching matrix 92 to an appropriate compressor/decompressor 82.

For voice operation from Class 5 switch 52, a voice signal carried overan associated unbundled analog line 62 is received at input port 70.Input port 70 performs electrical analog termination of the incomingunbundled analog line 62 and insures that the lines are properlyterminated. Input port 70 provides the voice signal to a correspondingA/D and D/A converter 76 in analog-to-digital and digital-to-analogconverter unit 74. Analog-to-digital and digital-to-analog converterunit 74 may also perform coding and decoding functions of a conventionalCODEC unit to include a ring and digit detection unit 75. A controlprocessor 77 may be part of analog-to-digital and digital-to-analogconverter unit 74 to supervise and control CODEC functionality. Adistinctive ring detection may also be employed to provide anoversubscription capability discussed in more detail later.Analog-to-digital and digital-to-analog converter unit 74 detects a ringcondition on unbundled analog line 62 and the corresponding A/D and D/Aconverter 78 places the voice signal into a digital format. Thedigitized voice signal passes through first switching matrix 90 where itis routed to a desired compressor/decompressor 82 incompressing/decompressing unit 80. The voice signal is compressed andpasses through second switching matrix 92 where it is routed to adesired packetizer/depacketizer 86 in packetizing/depacketizing unit 84.The voice signal in its packet format transfers through output port 88,possibly multiplexed with other packetized voice signals, and is passedto DSLAM device 66 over an appropriate output line through packet switch68 for ultimate delivery to office customer premises 12 or residencecustomer premises 14 over associated digital subscriber lines.

For voice operation to Class 5 switch 52, the voice signal is originatedat office customer premises 12 or residence customer premises 14, passesthrough DSLAM device 66 and packet switch 68, and is received at outputport 88 of voice gateway 64. Output port 88 demultiplexes the voicesignal provides the voice signal to an associatedpacketizer/depacketizer 86 in packetizing/depacketizing unit 84according to an available unbundled analog line 62. Thepacketizer/depacketizer 86 removes the voice signal from its transportframe. The voice signal then passes through second switching matrix 92for routing to an appropriate compressor/decompressor 82 incompressing/decompressing unit 80. Compressor/decompressor 82decompresses the voice signal into its full digital format. The voicesignal then passes through first switching matrix 90 for routing to anappropriate A/D and D/A converter 78 in analog-to-digital anddigital-to-analog converting unit 76. A/D and D/A converter 78 placesthe voice signal into its analog format. The voice signal is then placedonto its corresponding unbundled analog line 62 at input port 70. Thevoice signal then passes on to Class 5 switch 52 for further routingthrough public switched telephone network 50.

Voice gateway 64 may also support an oversubscription capability. Eachunbundled analog line 62 may be provisioned to carry voice traffic in a1:1 ratio where there are the same number of unbundled analog lines 62for each telephone number. Each unbundled analog line 62 may also beoversubscribed, for example in a 4:1 ratio, where there are fourtelephone numbers per unbundled analog line 62. Unbundled analog line 62may also be an Integrated Services Digital Network Basic Rate Interfaceline with a capability to transfer two simultaneous voice channels. Theuse of this type of line allows for the immediate doubling of callcapacity with or without oversubscription.

For outgoing calls toward Class 5 switch 52, a first telephone deviceassociated with a first one of the four telephone numbers may be in useand thus occupying its associated unbundled analog line 62. A secondtelephone device associated with a second one of the telephone numbersmay be put into use as long as there is a free unbundled analog line 62connected to voice gateway 64. Output port 88 determines if there is afree unbundled analog line 62 available for connection of the secondtelephone device, such as through a hunt group search. Output port 88 iscapable of connecting any telephone device of office customer premises12 and residence customer premises 14 to any available unbundled analogline 62 in order to support the oversubscription capability.

For incoming calls from Class 5 switch 52, voice gateway 64 is capableof detecting a distinctive ring given to each telephone number assignedto unbundled analog line 62. In the 4:1 oversubscription example, eachof the four telephone numbers has its own unique ring associatedtherewith. Voice gateway 64 determines which of the customer telephonedevices to route the call to according to the detected ring. Thoughdescribed with reference to a 4:1 ratio, other oversubscription ratiosmay be equally implemented through this technique.

Thus, it is apparent that there has been provided, in accordance withthe present invention, a method and apparatus for providing voicesignals to and from a telecommunications switch that satisfies theadvantages set forth above. Although the present invention has beendescribed in detail, it should be understood that various changes,substitutions, and alterations may be readily ascertainable by thoseskilled in the art and may be made herein without departing from thespirit and scope of the present invention as defined by the followingclaims.

1. A system for supporting oversubscription, comprising: atelecommunications switch operable to assign a plurality of telephonenumbers to a line, to receive an incoming call for one of the telephonenumbers, and to communicate the incoming call associated with thetelephone number using the line; and a voice gateway coupled to thetelecommunications switch using the line, the voice gateway operable toreceive the incoming call, to detect a unique distinctive ring assignedto the telephone number associated with the incoming call, and tocommunicate the incoming call according to the distinctive ring; whereinthe voice gateway processes the incoming call into the digital packetsaccording to the distinctive ring by identifying an address associatedwith the distinctive ring and assigning the address to the digitalpackets.
 2. The system of claim 1, wherein the address is an InternetProtocol (IP), Asynchronous Transfer Mode (ATM), or Frame Relay address.3. The system of claim 1, wherein the voice gateway communicates theincoming call by processing the incoming call into digital packetsaccording to the distinctive ring and communicating the digital packetsto a customer premises interface for further communication to a customerpremises, wherein the customer premises interface is a DigitalSubscriber Line Access Multiplexer (DSLAM) operable to communicate thedigital packets over a twisted pair in a local loop using a digitalsubscriber line.
 4. The system of claim 1, wherein the voice gateway isfurther operable to communicate the incoming call to a selected one of aplurality of output lines according to the distinctive ring.
 5. Thesystem of claim 1, wherein the telecommunications switch is furtheroperable to assign at least four telephone numbers to the line.
 6. Thesystem of claim 1, wherein the voice gateway is further operable toreceive an outgoing call originated at a customer premises, to identifyan available line from a plurality of lines coupled between thetelecommunications switch and the voice gateway, and to communicate theoutgoing call to the telecommunications switch using the available line.7. The system of claim 6, wherein the voice gateway communicates theoutgoing call by receiving digital packets, processing the digitalpackets into a voice signal, and communicating the voice signal to thetelecommunications switch using the available line.
 8. The system ofclaim 6, wherein the plurality of lines is a hunt group.
 9. The systemof claim 1, wherein: the telecommunications switch is a Class 5 switch;and the voice gateway is further operable to couple to the Class 5switch without using an overlay Class 5 switch or digital loop carrierarchitecture.
 10. The system of claim 1, wherein the line is anunbundled analog line.
 11. A voice gateway for supportingoversubscription of a line coupled to a telecommunications switch, thevoice gateway operable to receive a first incoming call with a firstdistinctive ring from the line and to communicate first incoming call toa first destination according to the first distinctive ring, the voicegateway further operable to receive a second incoming call with a seconddistinctive ring from the line and to communicate the second incomingcall to a second destination according to the second distinctive ring;wherein the voice gateway processes the first incoming call into thedigital packets according to the first distinctive ring by identifyingan address associated with the first distinctive ring and assigning theaddress to the digital packets.
 12. The voice gateway of claim 11,wherein the address is an Internet Protocol (IP), Asynchronous TransferMode (ATM), or Frame Relay address.
 13. The voice gateway of claim 11,wherein the voice gateway communicates the first incoming call byprocessing the first incoming call into digital packets according to thefirst distinctive ring and communicating the digital packets to acustomer premises, wherein the voice gateway communicates the digitalpackets to the customer premises using a Digital Subscriber Line AccessMultiplexer (DSLAM) operable to communicate the digital packets over atwisted pair in a local loop using a digital subscriber line.
 14. Thevoice gateway of claim 11, wherein the voice gateway is further operableto communicate the first incoming call to a selected one of a pluralityof output lines according to the first distinctive ring.
 15. The voicegateway of claim 11, wherein the voice gateway receives the secondincoming call after terminating the first incoming call.
 16. The voicegateway of claim 11, wherein the voice gateway is further operable tosupport oversubscription of at least 4:1.
 17. The voice gateway of claim11, wherein the voice gateway is further operable to receive an outgoingcall originated at a customer premises, to identify an available linefrom a plurality of lines coupled to the telecommunications switch, andto communicate the outgoing call to the telecommunications switch usingthe available line.
 18. The voice gateway of claim 17, wherein the voicegateway communicates the outgoing call by receiving digital packets,processing the digital packets into a voice signal, and communicatingthe voice signal to the telecommunications switch using the availableline.
 19. The voice gateway of claim 17, wherein the plurality of linesis a hunt group.
 20. The voice gateway of claim 11, wherein: thetelecommunications switch is a Class 5 switch; and the voice gateway isfurther operable to couple to the Class 5 switch without using anoverlay Class 5 switch or digital loop carrier architecture.
 21. Thevoice gateway of claim 11, wherein the lines are unbundled analog lines.22. A method for supporting oversubscription of a line coupled to atelecommunications switch, comprising: receiving a first incoming callwith a first distinctive ring from the line coupled to thetelecommunication switch; communicating the first incoming call to afirst destination according to the first distinctive ring; receiving asecond incoming call with a second distinctive ring from the line; andcommunicating the second incoming call to a second destination accordingto the second distinctive ring; wherein processing the first incomingcall into the digital packets according to the first distinctive ringfurther comprises: identifying an address associated with the firstdistinctive ring; and assigning the address to the digital packets. 23.The method of claim 22, wherein the address is an Internet Protocol(IP), Asynchronous Transfer Mode (ATM), or Frame Relay address.
 24. Themethod of claim 22, wherein communicating the first incoming call to thefirst destination according to the first distinctive ring furthercomprises: processing the first incoming call into digital packetsaccording to the first distinctive ring; and communicating the digitalpackets to a customer premises, wherein communicating the digitalpackets to the customer premises further comprises communicating thedigital packets to a customer premises interface for furthercommunications to the customer premises.
 25. The method of claim 24,wherein the customer premises interface is a Digital Subscriber LineAccess Multiplexer (DSLAM) operable to communicate the digital packetsover a twisted pair in a local loop using a digital subscriber line. 26.The method of claim 22, wherein communicating the first incoming call tothe first destination according to the first distinctive ring furthercomprises: selecting one of a plurality of output lines according to thefirst distinctive ring; and communicating the first incoming call usingthe selected output line.
 27. The method of claim 22, further comprisingterminating the first incoming call before receiving the second incomingcall.
 28. The method of claim 22, further comprising providing at least4:1 oversubscription of the line.
 29. The method of claim 22, furthercomprising: receiving an outgoing call from a customer premises;identifying an available line from a plurality of lines coupled to thetelecommunications switch; and communicating the outgoing call to thetelecommunications switch using the available line.
 30. The method ofclaim 29, wherein communicating the outgoing call to thetelecommunications switch further comprises: receiving digital packetsfrom a customer premises interface; processing the digital packets intoa voice signal; and communicating the voice signal to thetelecommunications switch using the available line.
 31. The method ofclaim 29, wherein the plurality of lines is a hunt group.
 32. The methodof claim 22, wherein: the telecommunications switch is a Class 5 switch;and the lines couple to the Class 5 switch without using an overlayClass 5 switch or digital loop carrier architecture.
 33. The method ofclaim 22, wherein the lines are unbundled analog lines.